com.google.cloud.dataflow.sdk.runners.inprocess

Class ForwardingPTransform<InputT extends PInput,OutputT extends POutput>

java.lang.Object

com.google.cloud.dataflow.sdk.transforms.PTransform<InputT,OutputT>

com.google.cloud.dataflow.sdk.runners.inprocess.ForwardingPTransform<InputT,OutputT>

All Implemented Interfaces:

HasDisplayData, Serializable

public abstract class ForwardingPTransform<InputT extends PInput,OutputT extends POutput>
extends PTransform<InputT,OutputT>

A base class for implementing PTransform overrides, which behave identically to the delegate transform but with overridden methods. Implementors are required to implement delegate(), which returns the object to forward calls to, and apply(PInput).

See Also:

Serialized Form

Field Summary

Fields inherited from class com.google.cloud.dataflow.sdk.transforms.PTransform

name

Constructor Summary

Constructors

Constructor and Description
ForwardingPTransform()

Method Summary

Modifier and Type	Method and Description
OutputT	apply(InputT input) Applies this PTransform on the given InputT, and returns its Output.
protected abstract PTransform<InputT,OutputT>	delegate()
<T> Coder<T>	getDefaultOutputCoder(InputT input, TypedPValue<T> output) Returns the default Coder to use for the given output of this single-output PTransform when applied to the given input.
String	getName() Returns the transform name.
void	populateDisplayData(DisplayData.Builder builder) Register display data for the given transform or component.
void	validate(InputT input) Called before invoking apply (which may be intercepted by the runner) to verify this transform is fully specified and applicable to the specified input.

Methods inherited from class com.google.cloud.dataflow.sdk.transforms.PTransform

getDefaultOutputCoder, getDefaultOutputCoder, getKindString, toString

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

ForwardingPTransform

public ForwardingPTransform()

Method Detail

delegate

protected abstract PTransform<InputT,OutputT> delegate()

apply

public OutputT apply(InputT input)

Description copied from class: PTransform

Applies this PTransform on the given InputT, and returns its Output.

Composite transforms, which are defined in terms of other transforms, should return the output of one of the composed transforms. Non-composite transforms, which do not apply any transforms internally, should return a new unbound output and register evaluators (via backend-specific registration methods).

The default implementation throws an exception. A derived class must either implement apply, or else each runner must supply a custom implementation via PipelineRunner.apply(com.google.cloud.dataflow.sdk.transforms.PTransform<InputT, OutputT>, InputT).

Overrides:

apply in class PTransform<InputT extends PInput,OutputT extends POutput>

validate

public void validate(InputT input)

Description copied from class: PTransform

Called before invoking apply (which may be intercepted by the runner) to verify this transform is fully specified and applicable to the specified input.

By default, does nothing.

Overrides:

validate in class PTransform<InputT extends PInput,OutputT extends POutput>

getName

public String getName()

Description copied from class: PTransform

Returns the transform name.

This name is provided by the transform creator and is not required to be unique.

Overrides:

getName in class PTransform<InputT extends PInput,OutputT extends POutput>

getDefaultOutputCoder

public <T> Coder<T> getDefaultOutputCoder(InputT input,
                                          TypedPValue<T> output)
                                   throws CannotProvideCoderException

Description copied from class: PTransform

Returns the default Coder to use for the given output of this single-output PTransform when applied to the given input.

Overrides:

getDefaultOutputCoder in class PTransform<InputT extends PInput,OutputT extends POutput>

Throws:

CannotProvideCoderException - if none can be inferred.

By default, always throws.

populateDisplayData

public void populateDisplayData(DisplayData.Builder builder)

Description copied from class: PTransform

Register display data for the given transform or component.

populateDisplayData(DisplayData.Builder) is invoked by Pipeline runners to collect display data via DisplayData.from(HasDisplayData). Implementations may call super.populateDisplayData(builder) in order to register display data in the current namespace, but should otherwise use subcomponent.populateDisplayData(builder) to use the namespace of the subcomponent.

By default, does not register any display data. Implementors may override this method to provide their own display data.

Specified by:

populateDisplayData in interface HasDisplayData

Overrides:

populateDisplayData in class PTransform<InputT extends PInput,OutputT extends POutput>

Parameters:

builder - The builder to populate with display data.

See Also:

HasDisplayData